Ink-jet printing has become a popular way of recording images on various media surfaces, particularly paper, for a number of reasons, including, low printer noise, capability of high-speed recording, and multi-color recording. Additionally, these advantages of ink-jet printing can be obtained at a relatively low price to consumers. Though there has been great improvement in ink-jet printing, improvements are followed by increased demands from consumers for higher speeds, higher resolution, full color image formation, increased stability, etc.
As new ink-jet inks and print engines are developed, several traditional characteristics are considered when evaluating the ink in conjunction with a printing surface or substrate. Such characteristics include edge acuity and optical density of the image on the surface, gloss, black to color bleed control, dry time of the ink on the substrate, adhesion to the substrate, lack of deviation in ink droplet placement, presence of all dots, resistance of the ink after drying to water and other solvents, long term storage stability, and long term reliability without pen material degradation or nozzle clogging. The long term reliability without material degradation or nozzle clogging becomes even more important with the advent of print engines that eject smaller drop volumes.
Under certain circumstances, ink formulations may become frothy, degrading the desired ink-jet characteristics. For example, if an ink becomes frothy, precise ink placement may be compromised, ink level readings in the ink reservoir may be inaccurate, and nozzle damage may occur.